Before going further, I really think installing from a tar.gz from
http://www.phpmyadmin.net is the best solution since you will have to configure your config.php file anyway...
Now...
First of all, you need to configure a yum repository were phpMyAdmin is available (and I seriously doubt there is one in the out-of-the-box config).
Then you need to make sure your are specifying the name with no typos. If in doubt, you could try to check with:
Code:
yum list *php*
yum list *Php*
An other option would be to find a phpMyAdmin rpm file, download it somewhere on your disk and install it like:
Code:
yum install [path/to/]downloadedFile.rpm